At least 58 people have died and hundreds have been injured Sunday night at a country-music concert in Las Vegas, the worst mass shooting in U.S. history, the Las Vegas police department said. Clark County Sheriff Joseph Lombardo said during a press conference that two police officers are in the hospital, one in critical condition and one with minor injuries. At least one other off-duty officer has died. As for those injured, “we are using the number of 515,” Lombardo said on Monday morning. “As you can tell, as the hours go by, that number continues to increase.”

The Las Vegas Police Department confirmed early Monday the suspected shooter is Stephen Paddock, age 64, who is dead. A police statement said Paddock was found dead when a SWAT team breached the hotel room on the 32nd floor of the Mandalay Bay Hotel from where Paddock had opened fire on the crowd of more than 22,000 who were attending the Route 91 Harvest Festival concert across the street. Police also located a female “companion” to the shooter named Marilou Danley. They later said Danley was located out of the country and was “no longer being sought out as a person of interest.” During an earlier press conference, Lombardo described the suspected shooter as “a lone-wolf-type actor.”

The confirmed death toll in the Las Vegas shooting surpassed the number in Orlando, Florida, where Omar Mateen, a gunman who had pledged allegiance to ISIS, killed 49 people at the Pulse nightclub in June 2016. Other recent gun rampages in the U.S. include the Sandy Hook school shooting in 2012 that killed 27 people and the Virginia Tech massacre in 2007 in which 32 people were killed.

Multiple videos posted on social media after the Las Vegas shooting show rounds of gunfire ringing out during a musical performance at the Route 91 Harvest festival a little after 10 p.m. Sunday. Photos show concertgoers dropping to the ground for cover and fleeing the scene amid panic. Lombardo noted that incorrect reports on social media suggested there were shootings at other resorts. “That has been proven to be false,” he said. Reports of explosives going off were also false, he added.

The country-music singer Jason Aldean was performing when the gunfire began, according to the Associated Press; the music stopped once the shots became audible. Witnesses reported first hearing gunfire coming from the upper floors of the nearby Mandalay Bay Resort and Casino, according to the Los Angeles Times, and heard multiple rounds of shooting. Police later confirmed that the shooting came from the 32nd floor of the hotel.

Flights were diverted from McCarran Airport in Las Vegas following the incident, and all activity at the airport was temporarily halted. MGM Resorts, which owns the Mandalay Bay hotel, stated on social media that law enforcement asked hotels in the vicinity to go on lockdown to ensure the safety of their guests.

People are seen running from the concert at the Mandalay Bay Resort and Casino. (David Becker / Getty Images)

Several hours after the shooting, Aldean posted on Instagram that he is “heartbroken,” calling the shooting “beyond horrific.”

“The President has been briefed on the horrific tragedy in Las Vegas. We are monitoring the situation closely and offer our full support to state and local officials.” White House Press Secretary Sarah Huckabee Sanders said in a statement. “All of those affected are in our thoughts and prayers.”

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On social media and television-news reports, the Las Vegas police department warned people to stay away from the Strip. Officials also provided a phone number that people can call to locate missing friends and members of their family.